A writer stumbles upon a long-hidden secret when he agrees to help former British Prime Minister Adam Lang complete his memoirs on a remote island after the politician's assistant drowns in a mysterious accident. In director Roman Polanski's tense drama, the author realizes that his discovery threatens some very powerful people who will do anything to ensure that certain episodes from Lang's past remain buried.

When a successful British ghostwriter (Ewan McGregor) agrees to complete the memoirs of former British Prime Minister Adam Lang (Pierce Brosnan), his agent assures him it is the opportunity of a lifetime. But the project seems doomed from the start, not least because his predecessor on the project, Lang's long-term aide, died in an apparent accident. The ghostwriter flies out to work on the project, in the middle of winter, at an oceanfront house in the fictional American village of Old Haven (an allusion to Vineyard Haven) on Martha's Vineyard. But the day he arrives, a former British foreign minister named Rycart accuses Lang of authorizing the illegal seizure of suspected terrorists and handing them over for torture by the CIA, a possible war crime. Lang faces the threat of prosecution by the International Criminal Court, unless he stays in the U.S. or goes to another country that does not recognize that court. The controversy brings reporters and protesters swarming to the security perimeter of the island home where Lang is staying with his wife, Ruth (Olivia Williams), and his personal assistant (and mistress), Amelia Bly (Kim Cattrall). As the ghostwriter works, he uncovers clues suggesting his predecessor may have stumbled on a dark secret concerning Lang and that somehow this information is hidden in the manuscript he left behind. During Lang's absence, the neglected and possibly vengeful Ruth sleeps with the writer. The writer meets an old man (Eli Wallach) living locally, who tells him that there is no possible way the current could have taken the body of the dead writer from the ferry where he disappeared to the beach location where it was discovered. The old man also reveals that a neighbor woman saw flashlights on the beach the night the body was discovered, but later fell down her stairs and went into a coma.